P1 (4/n): unit tests and examples use the level-list constructor

test_shifted_jets, test_shifted_storage, test_raw_exchange and
test_channel_root pass refinements/level_* lists; examples
fixed_patch_jet and fixed_periodic_patch pass refinements=[BOUNDS]
instead of the positional bounds. Assertions kept; the shifted-storage
case base_block-without-fine_block now expects the level-list rule
'blocked refined levels below' (same constraint).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/fixed_patch_jet.py

@@ -148,8 +148,8 @@ def main():
                   samples=[], status='running', last_synchronized_coarse_step=0)
     start, run = time.monotonic(), None
     try:
-        with CudaContext(0) as context, FixedPatchStepper(cfg, BOUNDS, context=context,
-                coarse_boundary='slot_reservoir') as run:
+        with CudaContext(0) as context, FixedPatchStepper(cfg, context=context,
+                coarse_boundary='slot_reservoir', refinements=[BOUNDS]) as run:
             p = run.patch
             masks = [np.ones(p.coarse_shape, bool), p.fine_kind == ACTIVE]
             masks[0][[0, -1]] = False